DENIERS SAY:

The greenhouse effect is just a theory; it hasn’t been proven by real-world data.

SCIENCE SAYS:

Two centuries of scientific research tell us the greenhouse effect is real.

Without the greenhouse effect generated by our atmosphere, heat from the sun would be quickly lost to space and the Earth would be an icy ball. Nearly 200 years of scientific research — including direct observations of the greenhouse effect in action — back up this reality. But although we do need the greenhouse effect, we certainly don’t need to make it stronger by pumping carbon pollution into the air. The more carbon we put into the atmosphere, the more heat we trap and the hotter it gets. And around the world, we’re already starting to see the negative effects of a greenhouse effect on steroids.

Additional info from The Climate Reality Project

The concept of the “greenhouse effect” is fairly new to non-scientists. In the U.S., for example, only about a third of Americans had heard the phrase by 1981.

Generations of scientists have poked and prodded at Fourier’s groundbreaking work, rejecting some of his ideas and building on others. For example, John Tyndall was the first to experimentally demonstrate that just a few trace gases in the atmosphere, including carbon dioxide, cause the greenhouse effect. And the heat-trapping ability of carbon dioxide has been repeatedly measured in laboratories around the world.

Evidence of the greenhouse effect doesn’t just come from labs, however; we also have real-world measurements of it in action. Remember that when sunlight enters Earth’s lower atmosphere, some of that energy warms the Earth’s surface. Most of the heat is then radiated from the surface and trapped by greenhouse gases in the atmosphere … which then recycle heat back to Earth again. Here’s the cool thing: Scientists at the U.S. Department of Energy’s Atmospheric Radiation Measurement program can actually measure the amount of heat recycled back to the Earth’s surface!

Importantly, Fourier’s main point about the greenhouse effect has stood the test of time: Our atmosphere helps keep the Earth warm by slowing the loss of heat to space.